That sounds like the cage I have for my SFS. I imagine you'd need more than one wheel and about 6 nest boxes, I think that might be kinda tight but I think it would really depend. Do they all get along (really well) and how much out of the cage time to they have?

The cage is outside, so whoever jumps on me first tends to be the one to get out and play. Also, are pouches ok instead of nest boxes? I notice the wood on the boxes absorbs the urine and stink! Pouches get washed once a week.